High-Voltage Metal-Oxide-Semiconductor (HVMOS) devices are widely used in many electrical devices, such as Input/output (I/O) circuits, Central Computing Unit (CPU) power supplies, power management systems, AC/DC converters, etc. HVMOS devices typically include drain regions and laterally-diffused drain regions enclosing the drain regions. Laterally-diffused drain regions are typically well regions having lower doping concentrations than the drain regions. The breakdown voltages of the HVMOS devices are accordingly high.